1. Technical Field
This invention is related to the field of integrated circuit implementation, and more particularly to the implementation of power management circuits.
2. Description of the Related Art
Computing systems may include one or more systems-on-a-chip (SoC), which may integrate a number of different functions, such as, graphics processing, onto a single integrated circuit. With numerous functions included in a single integrated circuit, chip count may be kept low in mobile computing systems, such as tablets, for example, which may result in reduced assembly costs, and a smaller form factor for such mobile computing systems.
In some SoC designs, processors included in the SoC may enter an inactive state upon completing certain computing tasks to reduce power consumption or to reduce the emission of electromagnetic interference (EMI). Peripheral circuitry may similarly enter idle states to further conserve system power consumption or reduce EMI. Another method for reducing power is to reduce the operating frequency of the system when there is a low demand for processing power. A lower operating frequency reduces the dynamic current of the system. In addition, functional blocks not in use may be powered down or placed into low power idle states.
In some system-on-a-chip (SoC) designs, a voltage regulator may be used to maintain the voltage level of the power supply used throughout the SoC to prevent the voltage level from rising to a level which may damage the circuits. Some voltage regulating systems may be capable of providing multiple voltage levels such that the system voltage level may be adjusted to match the power requirements in certain states. For example, the voltage level of the power supply may be reduced when the processor is in an idle state.
The method on which many voltage regulator designs operate may be susceptible to problems when there is a sudden change in the current consumption from the logic circuits to which the regulator is providing power. A sudden increase in current consumption may cause a temporary drop in the voltage level of the output of the regulator while the regulator adjusts to compensate. If the voltage level drops below a minimum voltage level necessary to operate the logic circuits, even briefly, a logic state within the logic circuits may be corrupted, which may lead to indeterminate behavior and a possible processing exception.
A known SoC device includes a circuit that increases a system voltage to a safe voltage level, higher than the normal operating voltage level, in response to a temperature measurement that indicates the temperature of the SoC is rising above a nominal level. In addition to increasing the system voltage responsive to a temperature measurement, this circuit will increase the system voltage responsive to an increase to the frequency of the processor's clock. The increase of the system voltage to the safe voltage level lasts approximately 10 microseconds and then returns to the normal operating voltage level.